
<!-- content start -->
.content .ad, .content .user_login_regist {
    clear: both;
    margin-bottom: 10px;
}
.ad h2{
    text-align: center;
}
.user_login_regist .regist_form {
    float: left;
    width: 500px;
}
.user_login_regist .login_form {
    float: right;
    width: 440px;
    margin-left: 5px;
}
<!-- content end -->